Python NameError：名称未定义（与默认输入参数类型有关）

我对我打电话的事实有疑问len(myByteArray)在我声明的函数的输入参数中。我希望它成为默认参数，但 Python 似乎不喜欢它。myByteArray属于类型bytearray. See 关于 bytearray 的文档在这里。我正在访问它的内置find功能，记录在这里（参见“bytes.find”）。

我的功能：

def circularFind(myByteArray, searchVal, start=0, end=len(myByteArray)):
    """
    Return the first-encountered index in bytearray where searchVal 
    is found, searching to the right, in incrementing-index order, and
    wrapping over the top and back to the beginning if index end < 
    index start
    """
    if (end >= start):
        return myByteArray.find(searchVal, start, end)
    else: #end < start, so search to highest index in bytearray, and then wrap around and search to "end" if nothing was found 
        index = myByteArray.find(searchVal, start, len(myByteArray))
        if (index == -1):
            #if searchVal not found yet, wrap around and keep searching 
            index = myByteArray.find(searchVal, 0, end)
        return index 

尝试使用上述函数的示例：

#-------------------------------------------------------------------
#EXAMPLES:
#-------------------------------------------------------------------
#Only executute this block of code if running this module directly,
#*not* if importing it
#-see here: http://effbot.org/pyfaq/tutor-what-is-if-name-main-for.htm
if __name__ == "__main__": #if running this module as a stand-alone program
    import random
    random.seed(0)

    bytes = bytearray(100)
    for i in range(len(bytes)):
        bytes[i] = int(random.random()*256)

    print(list(bytes)); print();

    print('built-in method:')
    print(bytes.find(255))
    print(bytes.find(2,10,97))
    print(bytes.find(5,97,4))

    print('\ncircularFind:')
    print(circularFind(bytes,255))
    print(circularFind(bytes,2,10,97))
    print(circularFind(bytes,5,97,4))

Error:

NameError：名称“myByteArray”未定义

如果我只是删除我的默认参数（=0 and =len(myByteArray)），但是，它工作得很好。但是......我真的想要那些默认参数，以便start and end参数是可选的。我该怎么办？

在 C++ 中，这很容易，因为参数类型是在编写函数时指定的。

Python 默认参数在定义函数时计算。相反，你想要这样的东西：

def circularFind(myByteArray, searchVal, start=0, end=None):
    """
    Return the first-encountered index in bytearray where searchVal 
    is found, searching to the right, in incrementing-index order, and
    wrapping over the top and back to the beginning if index end < 
    index start
    """
    if end is None:
        end = len(myByteArray)
    # continue doing what you were doing